add test for Mysql: DROP INDEX index_name ON tbl_name

h2/src/test/org/h2/test/db/TestCompatibility.java

@@ -399,6 +399,8 @@ public class TestCompatibility extends TestBase {
         stat.execute("ALTER TABLE TEST_COMMENT_ENGINE ADD CONSTRAINT CommentUnique UNIQUE (SOME_ITEM_ID)");
         stat.execute("ALTER TABLE TEST_COMMENT_ENGINE DROP INDEX CommentUnique");
         stat.execute("DROP INDEX SOME_ITEM_ID ON TEST_COMMENT_ENGINE");
+        stat.execute("CREATE INDEX IDX_ATTACHMENT_ID ON TEST_COMMENT_ENGINE (ATTACHMENT_ID)");
+        stat.execute("DROP INDEX IDX_ATTACHMENT_ID ON TEST_COMMENT_ENGINE");
 
         conn.close();
         conn = getConnection("compatibility");